I can tell you BHC was only at a moderate flow when I saw it about 1430 this afternoon, not a lot of water to be honest.Tthe kind of rain that facilitated most soaking in rather than running off. The Torrens was disinteresting tonight when I walked along it between 2200 and 2300.
I don't think the soaking in is to do with the "kind of rain", but rather to do with the summer and autumn being dry (24% below average rainfall for the previous six months) and clay soil having contracted due to it also being so hot as well as dry.
Wait until tomorrow and the level will rise along Brownhill Creek as the runoff works its way down, and being so flat (the flow is driven by the water level rather than gravity) it will stick around for a couple of days after the rain stops.
This was a fairly large rain event, though not extreme, if you look at the numbers. It was enough to take us to 45% of the monthly mean rainfall for June (our wettest month, at that) in the first 12 hours of the month (rainfall is measured daily at 9am from the previous 24 hours). If it had happened a day earlier, the total for January-May would have been 5% over average instead of the 18% under it was.
The best news with this rain is that a good amount managed to get over the Mt Lofty Ranges - Murray Bridge Airport has had 54mm so far.
Wow, that's a lot of rain- I bet the Torrens is actually flowing.
The current plan for maintaining the Torrens (for preventing algal blooms and keeping the riverbed moist to avoid problems for structures) has at least a slow flow going all the way along, every day of the year. If you go to the weir at the western end of the Torrens Lake you will almost never see it without water flowing over the top, even in the middle of summer. This water comes from the spring-fed creeks and from the reservoir at Kangaroo Creek.
The Onkaparinga is a different issue. Strategies may have changed a little now that Happy Valley Reservoir is also fed from the big white desal plant with the trunk, but it definitely used to be the case that nothing other than what was needed to feed Happy Valley (via the Clarendon weir and pipeline) would be released from Mount Bold if the level there was low, they would happily let the Onkaparinga between Clarendon and Old Noarlunga dry up.